See: https://github.com/QwertyManiac/cassandra-cdh4/blob/master/src/java/org/apache/cassandra/io/sstable/Descriptor.java
Btw, cassandra "support" loves to send you to look at code, so download the code and get familiar with the basic structure (somehow).
public static final Version LEGACY = new Version("a"); // "pre-history"
// b (0.7.0): added version to sstable filenames
// c (0.7.0): bloom filter component computes hashes over raw key bytes instead of strings
// d (0.7.0): row size in data component becomes a long instead of int
// e (0.7.0): stores undecorated keys in data and index components
// f (0.7.0): switched bloom filter implementations in data component
// g (0.8): tracks flushed-at context in metadata component
// h (1.0): tracks max client timestamp in metadata component
// hb (1.0.3): records compression ration in metadata component
// hc (1.0.4): records partitioner in metadata component
// hd (1.0.10): includes row tombstones in maxtimestamp
// he (1.1.3): includes ancestors generation in metadata component
// hf (1.1.6): marker that replay position corresponds to 1.1.5+ millis-based id (see CASSANDRA-4782)
// ia (1.2.0): column indexes are promoted to the index file
// records estimated histogram of deletion times in tombstones
// bloom filter (keys and columns) upgraded to Murmur3
// ib (1.2.1): tracks min client timestamp in metadata component
